Wrap film with polyisobutylene succinic anhydride

ABSTRACT

A thermoplastic wrap film including polyisobutylene succinic anhydride (PIBSA) is disclosed herein.

PRIORITY CLAIM

This application claims priority under 35 U.S.C. § 119(e) to U.S.Provisional Application Ser. No. 62/931,306 filed Nov. 6, 2019, which isexpressly incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to a wrap film such as a cling filmand/or a stretch film having cling properties. More particularly, thepresent disclosure relates to a film including polyisobutylene succinicanhydride (PIBSA), which shows improved cling properties with chemicallypolar materials such as metal and glass.

BACKGROUND

It is often desirable to wrap product or contents for storage,transport, security, protection from the elements, protection fromdamage, and the like, or for any other reason. A film may be providedthat can cling and/or adhere to an underlying product or substrate,including polar material such as glass, fiberglass, metal, and the like.

SUMMARY

According to the present disclosure, a thermoplastic film includingpolyisobutylene succinic anhydride (PIBSA) is disclosed.

In illustrative embodiments, a thermoplastic film may include PIBSA inan amount of about 0.2% to about 10% by weight. A thermoplastic filmwith PIBSA may demonstrate improved cling properties with polarsubstrates such as fiber glass or metal, for example.

In one aspect, for instance, a thermoplastic film is provided havingabout 0.5% to about 10% by weight polyisobutylene succinic anhydride(PIBSA).

In another aspect, for instance, a thermoplastic film formulation isprovided that has about 55% by weight linear low density polyethylene(LLDPE), about 38% by weight low density polyethylene (LDPE), and about5% by weight PIBSA.

In yet another aspect, for instance, a thermoplastic film formulation isprovided having at least about 66% by weight LLDPE, at least about 12%by weight LDPE, and at least about 5% by weight PIBSA.

Additional features of the present disclosure will become apparent tothose skilled in the art upon consideration of illustrative embodimentsexemplifying the best mode of carrying out the disclosure as presentlyperceived.

BRIEF DESCRIPTIONS OF THE DRAWINGS

The detailed description particularly refers to the accompanying FIGURESin which:

FIGURE is an Illustration of a Test Used to Measure Cling or Adhesion ofa glass fiber to film.

DETAILED DESCRIPTION

Embodiments now will be described more fully hereinafter with referenceto the accompanying FIGURE and Tables, in which some, but not allembodiments are shown. As used in the specification, and in the appendedclaims, the singular forms “a”, “an”, “the”, include plural referentsunless the context clearly dictates otherwise.

The terms “substantial” or “substantially” may encompass the whole asspecified, according to certain embodiments, or largely but not thewhole specified according to other embodiments.

Illustrative embodiments of this disclosure relate to a thermoplasticfilm such as a polyolefin film having cling properties. The film may bea monolayer film or a multilayer film. For stretch wrap applications, orfor any other reason, the film may have cling properties so that it maycling or adhere to itself and/or to one or more items, products, and/ormaterials or the like for which the stretch wrap is intended to wrap,for example.

In some embodiments, the film may generally include a polymercomposition yielding a relatively high cling. For example, the clingforce may be measured by testing pursuant to ASTM D5458, and/or may beabout 30 grams or more, may be about 500 grams or less, and/or may be inthe range of about 30 grams to about 1000 grams, and/or in the range ofabout 30 grams to about 500 grams, for example, about 100 grams. It isunderstood that the cling force may be modified and/or vary depending onthe film application. In some embodiments, the cling force may be about40 g/in or more. The thermoplastic film may include a polyolefin such aspolyethylene, polypropylene, an ethylene vinyl acetate copolymer, and/orethylene methyl acrylate copolymer (EMA), and a tackifying resin.

The film may include cling additives, or additives that improve theclinging and/or adhering properties of the film. Useful cling additivesand/or tackifiers or tackifying resins may include flexomer, plastomer,thermoplastic elastomer, and polyisobutylene (PIB). For example, a PIBadditive may have a number average molecular weight in the range fromabout 1,000-3,000, or about 1200-1800, as measured for example by vaporphase osmometry. Polar groups may be added to PIB, for example byreaction with maleic anhydride to provide polyisobutylene succinicanhydride (PIBSA). Adding PIBSA to a thermoplastic and/or polyolefinfilm for cling was previously unknown. Unexpected results were achievedwhen adding PIBSA to a polyolefin film, for example, a film or a filmlayer with the characteristics described above and elsewhere herein. Itwas found that a film including PIBSA had approximately double the clingor adhesion to a glass fiber.

In some embodiments, about 0.2% to about 10% PIBSA may be added to athermoplastic film formulation. For example, if the film is a singlelayer or monolayer film, the PIBSA may comprise a higher percentage ofthe weight of the film formulation than if one or more additional layersare added. In a monolayer film, for example, the amount of PIBSA may beabout 1% to about 10.0% by weight of the film and/or the filmformulation. In a multilayer film, such as a three layer or five layerfilm, for example, one, all, or less than all of the layers may includePIBSA and/or the weight of PIBSA may be relatively lower than amonolayer film. For example, in a multilayer film, the amount of PIBSAmay be between about 0.2% and about 10% of the weight of the multilayerfilm. In some films and/or film formulations, the amount of PIBSA may bemore than about 0.2%, more than about 0.4%, more than about 0.5%, morethan about 1%, more than about 2%, more than about 3%, more than about4%, more than about 5%, more than about 6%, more than about 7%, morethan about 8%, and/or more than about 9%. In some films and/or filmformulations, the amount of PIBSA may be less than about 15%, less thanabout 14%, less than about 13%, less than about 12%, and/or less thanabout 11%.

In some monolayer films and/or film formulation embodiments, the amountof PIBSA may be less than about 15% and more than about 1%, less thanabout 13% and more than about 2%, less than about 12% and more thanabout 5%, less than about 12% and more than about 8%, and/or about 10%.In some multilayer films and/or film formulation embodiments, the amountof PIBSA may be less than about 10% and more than about 0.2%, less thanabout 5% and more than about 0.2%, less than about 2% and more thanabout 0.2%, less than about 2% and more than about 0.4%, and/or about0.5%

In one example, a film formulation includes about 55% by weight linearlow density polyethylene (LLDPE), about 38% by weight low densitypolyethylene (LDPE), about 1% by weight antiblock concentrate, about 1%by weight process aid, and about 5% by weight PIBSA. The PIBSA in thisexample is Dovermulse H-1000, commercially available from Dover ChemicalCorporation of Dover, Ohio. The resulting PIBSA film displayed about a180 gram cling or adhesion force on a glass fiber, as measured bypulling the glass fiber 200 as shown in FIG. 1 . In conducting the test,a single strand of glass fiber 200 that was 8.5″ long was appliedlengthwise to a film strip 100 that was about 12″ long by 1″ wide. InFIGURE, which is not to scale, film 100 is shown as a rectangle withstrand or glass fiber 200 placed or pressed thereon. The arrows in FIG.1 represent the relative motion or pull force F used to measure cling oradhesion. A control experiment was conducted in the same way, but to afilm using PIB instead of PIBSA, resulting in about a 90 gram cling oradhesion force. The example using PIBSA was provided by adding the PIBSAto a polyethylene melt and extruding into a film at temperatures up toabout 450 degrees Fahrenheit.

In another example, a film formulation includes about 76% LLDPE, about12% LDPE, 7% white UVI polythene masterbatch, and 5% PIBSA. In someembodiments, a film formulation may include between about 56% and about86% LLDPE, between about 8% LDPE and about 16% LDPE, between about 2%and about 12% UVI polythene, and/or between about 0.2% and about 10%PIBSA.

The film may further comprise additional resins and additives. Forexample, the film may comprise a puncture resistant resin. In anotherexample, the film may also comprise a low density polyethylene (LDPE)resin having a density of between about 0.91 and 0.94 g/cm³, a LLDPEresin having a density of between about 0.915 and 0.940 g/cm³, and/or avery low density polyethylene (VLDPE) resin having a density of betweenabout 0.88 and 0.915 g/cm³.

In some embodiments, polyethylene resins are utilized in the film, andare further blended or alloyed with minor amounts, e.g., up to about 20%by weight total, of one or more other suitable resins to achieve adesired range of physical/mechanical properties in the film product. Insome embodiments, film additives such as antioxidants, UV stabilizers,pigments, dyes, etc., are utilized in the film. It is understood thatsome additives, such as antioxidants, for example, may be provided withthe resin instead of or in addition to being added separately.

The polyolefin film described above may be provided in substantially asingle layer or monolayer structure, or it may be provided as a layer ofa multilayer film structure. Generally, embodiments of the film 100 areconstructed according to conventional practices. The film 100 may bemanufactured utilizing blown-film or cast-film co-extrusion. In oneembodiment, a cast-film manufacturing process provides resin materialsare heated to their molten state, and their viscosities are coordinatedto prepare multilayer films in a uniform manner. The molten materialsare conveyed to a co-extrusion adapter that combines the moltenmaterials to form a multilayer co-extruded structure. The layeredpolymeric material is transferred through an extrusion die opened to apredetermined gap commonly in the range of between about 0.05 in (0.13cm) and 0.012 in (0.03 cm). The material is then drawn down to theintended gauge thickness by means of a primary chill or casting rollmaintained at between about 50° F. to about 130° F. Typical draw downratios range from between about 5:1 to about 40:1.

The overall thickness of the monolayer or multilayer film can varywidely according to end use specifications, but is generally in therange of the typical thicknesses for stretch wrap films. In oneembodiment of the present invention, the overall film 100 thickness isbetween about 0.012 mm to about 0.125 mm. In one embodiment, the film100 thickness is about 0.025 mm.

Once manufactured, in some embodiments, the film or any layer thereofcan be post-formation treated by implementing operations such as coronadischarge, chemical treatment, flame treatment, etc., to modify theprintability or ink receptivity of the surface(s) or to impart otherdesirable characteristics thereto.

In accordance with embodiments of the invention, the film may beprovided in a non-stretched, i.e., unoriented, or merely a modestlystretched state prior to use. The film 100 is capable of being stretchedfrom at least between about 40% and 400% during a final goods wrappingstep.

In accordance with embodiments of the present invention, the film clingproperties are unexpectedly improved. These advantageous results may bea proximate result of the specific compositions utilized in the filmwith several embodiments of the present disclosure. With the addition ofPIMA in the film and/or the film formulation, the film has improvedcling with polar substrates, such as the fiberglass strand 200 used intesting and shown in FIGURE.

A monolayer film or multilayer film including PIBSA may be provided inany of a variety of ways, for example, by blowing the film or castingthe film, or any combination thereof. For example, it has been foundthat PIB and/or PIBSA migrates to the surface of a film within daysafter extrusion, and does not block bubble during the filmmanufacturing. PIB and PIBSA were also found to provide a better clingbetween the relatively less smooth surfaces of a blown film. Forexample, an effective amount of PIBSA may migrate to at least onesurface of the film to provide a cling force, for example, a cling forceof at least about 40 g/in.

As used herein, the term “comprising” means various components can beemployed in the methods, formulations, and compositions with or withoutadditional or alternative components. Accordingly, the terms “consistingessentially of” and “consisting of” are embodied in the term comprising.

Modifications and variations may be practiced by those of ordinary skillin the art without departing from the spirit and scope. In addition, itshould be understood that aspects of the various embodiments may beinterchanged in whole or in part. Furthermore, those of ordinary skillin the art will appreciate that the foregoing description is by way ofexample only, and it is not intended to limit the scope of that which isdescribed in the claims. Therefore, the spirit and scope should not belimited to the exemplary description of the versions contained herein.

I claim:
 1. A thermoplastic film, comprising: about 0.2% to about 10% byweight polyisobutylene succinic anhydride (PIBSA); wherein the film is amultilayer film; and wherein the multilayer film includes at least threelayers.
 2. The film of claim 1, wherein the film comprises at least oneof a polyethylene and a polypropylene.
 3. The film of claim 2, whereinthe film comprises at least 80% polyethylene, polypropylene, or blendsthereof.
 4. The film of claim 1, wherein the film is produced by blownextrusion.
 5. The film of claim 1, wherein the film is produced by castextrusion.
 6. The film of claim 1, wherein the film includes betweenabout 1% and about 12% PIBSA.
 7. The film of claim 1, wherein themultilayer film structure includes between about 0.2% and about 2.0%PIBSA.
 8. A thermoplastic film formulation, comprising: about 55% byweight linear low density polyethylene (LLDPE), about 38% by weight lowdensity polyethylene (LDPE), and about 5% by weight PIBSA.
 9. Thethermoplastic film formulation of claim 8, further comprising about 1%by weight antiblock concentrate.
 10. The thermoplastic film formulationof claim 8, further comprising about 1% by weight process aid.
 11. Athermoplastic film formulation, comprising: at least about 66% by weightLLDPE; at least about 12% by weight LDPE; and at least about 5% byweight PIBSA.
 12. The thermoplastic film formulation of claim 11,further comprising about 7% white UVI polythene masterbatch.
 13. Thethermoplastic film formulation of claim 11, further comprising at leastabout 76% by weight LLDPE.